<html>
<header>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js"></script>

<script type="text/javascript">

$(document).ready(function(){
  $(".addbutton").click(function(){
   
       $(".selectoption").append(
         '<li><input type="text" name="field[]" class="textbox" />' + 
         '<input type="button" class="removebutton" value="remove"/></li>'
       );
     });
  }

);

</script>
</header>

<body>



<div class="selectoption">
<ul class="addedfields">
<li><input type="text" name="field[]" class="textbox" />
<input type="button" class="removebutton" value="remove"/></li>
</ul>
<div>

<input type="button" class="addbutton" value="add"/>

</body>
</html>
